GI Hormones & Physiology Flashcards

1
Q

What do gastric parietal cells produce?

A

HCl, intrinsic factor

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2
Q

What do chief cells produce?

A

Pepsinogen

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3
Q

What do G cells produce?

A

Gastrin

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4
Q

What do mucous neck cells produce?

A

Bicarbonate mucus

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5
Q

What is pepsin?

A

Proteolytic enzyme that hydrolyzes peptide bonds

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6
Q

What is intrinsic factor?

A

Protein secreted by the parietal cells that combines with vitamin B12 and enables absorption in the terminal ileum

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7
Q

What 3 substances stimulate HCl release by parietal cells?

A
  1. Histamine
  2. Acetylcholine
  3. Gastrin
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8
Q

What is the enterohepatic circulation?

A

Circulation of bile acids from the liver to the gut and back to the liver via the portal vein

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9
Q

Where are most of the bile acids absorbed?

A

Terminal ileum

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10
Q

How many times is the entire bile acid pool circulated during a typical meal?

A

Twice

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11
Q

What are the stimulators of gallbladder emptying?

A

Cholecystokinin, vagal input

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12
Q

What are the inhibitors of gallbladder emptying?

A

Somatostatin, sympathetics, vasoactive intestinal peptide (VIP)

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13
Q

What is the source of cholecystokinin?

A

Duodenal mucosal cells

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14
Q

What stimulates the release of cholecystokinin?

A

Fat, protein, amino acids, HCl

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15
Q

What inhibits the release of cholecystokinin?

A

Trypsin, chymotrypsin

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16
Q

What are the actions of cholecystokinin?

A
  1. Empties gallbladder
  2. Opens ampulla of Vater
  3. Slows gastric emptying
  4. Stimulates pancreatic acinar cell growth and release of exocrine products
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17
Q

What is the source of secretin?

A

Duodenal cells (argyrophilic S cells)

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18
Q

What stimulates the release of secretin?

A

pH < 4.5, fat in the duodenum

19
Q

What inhibits the release of secretin?

A

High pH in duodenum

20
Q

What are the actions of secretin?

A
  1. Releases pancreatic bicarbonate, enzymes, and water
  2. Releases bile and bicarbonate
  3. Decreases LES tone
  4. Decreases release of gastric acid
21
Q

What is the source of gastrin?

A

G cells

22
Q

What stimulates the release of gastrin?

A
  1. Stomach peptides and amino acids
  2. Vagal input
  3. Calcium
23
Q

What inhibits the release of gastrin?

A

pH < 3.0, stomatostatin

24
Q

What are the actions of gastrin?

A

Release of HCl from parietal cells; trophic effects on mucosa of the stomach and small intestine

25
Q

What is the source of somatostatin?

A

Pancreatic D cells

26
Q

What stimulates the release of somatostatin?

A

Food

27
Q

What are the actions of somatostatin?

A

Globally inhibits GI function

28
Q

What is the purpose of the colon?

A

Reabsorption of water and storage of stool

29
Q

What is the main small bowel nutritional source?

A

Glutamine

30
Q

What is the main nutritional source of the colon?

A

Butyrate (SCFA)

31
Q

Where is calcium absorbed in the GI tract?

A

Duodenum actively, jejunum passively

32
Q

Where is iron absorbed in the GI tract?

A

Duodenum

33
Q

Which hormone primarily controls gallbladder contraction?

A

CCK

34
Q

What supplement does a patient need after removal of the terminal ileum or stomach?

A

Vitamin B12

35
Q

What are the main constituents of bile?

A

Water, phospholipids, bile acids, cholesterol, bilirubin

36
Q

What are most gallstones made of?

A

Cholesterol

37
Q

How do opiates affect the bowel?

A

By stimulating sodium absorption and inhibiting secretion in the ileum as well as decreasing GI motility by incoordinated peristalsis (therefore, place patients on stool softeners)

38
Q

Which electrolytes does the colon actively absorb?

A

Na, Cl

39
Q

Which electrolytes does the colon actively secrete?

A

Bicarbonate (plays a role in diarrhea causing the patient to have a normal anion gap acidosis)

40
Q

Which electrolytes does the colon passively secrete?

A

K

41
Q

What is the gastrocolic reflex?

A

Increased secretory and motor functions of the stomach result in increased colonic motility

42
Q

What is the blood supply to the liver?

A

75% from portal vein

25% from hepatic artery

43
Q

What are Peyer patches?

A

Nodules of lymphoid tissue with B and T cells in the small intestine that selectively sample luminal antigens found in the terminal ileum